Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

998
FXUS63 KLOT 272251
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
551 PM CDT Wed May 27 2026

.KEY MESSAGES...

- Generally warm and dry conditions expected through early next
  week.

- Daily lake breezes will keep temperatures cooler near Lake
  Michigan, with a couple of back door cold fronts bringing
  cooler conditions farther inland Thursday and again Saturday.

- Building waves and dangerous currents are expected at
  Illinois and Indiana Lake Michigan beaches late this evening
  through Thursday night.

&&

.DISCUSSION...
Issued at 113 PM CDT Wed May 27 2026

Early afternoon GOES water vapor imagery depicts a fairly stout
mid- level short wave propagating south-southeastward across
southwestern Ontario and the northern/eastern Great Lakes
region. At the surface, a cold frontal boundary stretched from
New England, west across the lower Great Lakes, then northwest
across Wisconsin into northern Plains. This cold front will be
given a southward nudge later today and tonight in the wake of
the aforementioned short wave, and enhanced by building surface
high pressure across the northern Lakes in the subsident wake of
this feature tonight. Ahead of the front, mostly sunny skies
have allowed temperatures to warm into the mid 80s (heading for
upper 80s/near 90 later this afternoon west) across much of the
forecast area, with upper 60s/low 70s closer to the Lake
Michigan shore where light onshore lake breeze winds have
developed. Farther north, scattered thunderstorms are expected
to develop along/ahead of the front by late afternoon, and drift
south- southwest across central/southern WI as the front pushes
south into early evening. Preponderance of high-res CAM
guidance indicates this activity will dissipate across southern
Wisconsin with the loss of diurnal heating this evening. Will
maintain a dry forecast for the cwa, though have maintained some
"silent" (<10%) pops along the IL/WI border through mid-evening
and will monitor convective trends in case a stray shower/storm
approaches the area.

The main impact from the cold front for us will be breezy
northeast winds which will develop behind the boundary later
this evening, and persist through Thursday and into Thursday
night. Gusty winds around 25 mph will result in building waves
on southern Lake Michigan during this period, leading to high
waves and dangerous currents for our Illinois and Indiana Lake
Michigan beaches. A Beach Hazard Statement remains in effect for
this through late Thursday night when winds/waves will
gradually subside.

Away from the lake shore, a period of dry and seasonably warm
weather will continue into the weekend, as the upper level
pattern evolves into an "Omega Block" with a persistent upper
level ridge axis focused near/just west of the Mississippi
Valley and deep upper level troughs over the east and west
coasts. Surface high pressure will continue to settle southward
across WI/MI/LM Thursday and across the local area by Friday.
This will allow the breezy northeast winds to ease, and diminish
the degree of lake-cooling. Highs on Thursday are expected to
range from the 60s along the shore to the lower 80s well west
and south of the lake. Lighter onshore winds on Friday will
allow for 70s near the shore and low to mid-80s inland with
highest temps west toward the I-39 corridor. Overnight lows will
generally be in the 50s. Current ensemble guidance then
indicates another mid-level short wave will dig south-southeast
across the eastern Lakes and New England Friday night into
Saturday, which for our area looks to bring another
northeasterly wind enhancement Saturday and Saturday night with
additional lake cooling and the potential for another increased
Lake Michigan swim risk.

Not much change in the pattern is expected until early-mid next
week, when global ensembles currently indicate a breakdown of
the Omega Block across the central CONUS. Until then however,
our forecast remains generally dry and seasonably warm (upper
70s and 80s) with varying degrees of lake cooling.

Ratzer

&&

.AVIATION /00Z TAFS THROUGH 06Z FRIDAY/...
Issued at 552 PM CDT Wed May 27 2026

There are no aviation concerns through the TAF period.

Winds at most terminals this evening are somewhat light (5-10kt)
and out of the east-northeast (wind direction 030 to 060) in the
wake of a lake breeze. The wind shift should reach RFD within a
few hours.

As a surface high pressure system centered over Lake Superior
continues building southward through the evening and overnight
hours, a reinforcing push of north to northeasterly winds will
arrive before daybreak and cause surface speeds to increase to
the 10-12kt range with occasional gusts to 20 kt. Such winds
will prevail through the afternoon before easing toward and
especially after sunset at the end of the TAF period.

Skies will remain largely clear outside of a few clouds based
near 35kft skirting overhead tomorrow.

Borchardt

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Air Quality Alert until 6 AM CDT Thursday for ILZ005-ILZ006-
     ILZ012-ILZ013-ILZ020-ILZ021-ILZ103-ILZ104-ILZ105-ILZ106-
     ILZ107-ILZ108.

     Beach Hazards Statement from 10 PM CDT this evening through
     late Thursday night for ILZ006-ILZ103-ILZ104.

IN...Air Quality Alert until midnight CDT tonight for INZ001-INZ002-
     INZ010-INZ011.

     Beach Hazards Statement from 1 AM CDT Thursday through late
     Thursday night for INZ001-INZ002.

LM...Small Craft Advisory from 10 PM this evening to 10 PM CDT
     Thursday for the IL nearshore waters.

     Small Craft Advisory from 1 AM Thursday to 1 AM CDT Friday for
     the IN nearshore waters.

&&

$$

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